NiL are good electro-catalysts for water oxidation in phosphate or carbonate buffers. The results point out that the active oxidizing agents are L(X)NiOH, where X = POH or COH formed from LNiXvia a mechanism involving an acid catalyzed O-P or O-C bond heterolysis. Carbonate behaves differently from phosphate as it is a non-innocent ligand and it can be oxidized.

Monovalent nickel is used as a catalyst in a diversity of important chemical systems due to its properties as a strong reducing agent. However, monovalent nickel is unstable in homogeneous systems; its lifetime is very short, and therefore, its efficiency as a catalyst is quite limited. In this article, we demonstrate the catalytic capabilities of Ni(I)(1,4,8,11‐tetraazacyclotetradecane)+ as a reducing and catalytic agent by its entrapment in the silica sol gel matrix. The EPR results indicate that the sol‐gel matrix plays two roles: it inhibits the common mechanism of Ni(I)L+ decomposition in aqueous solutions, and it also facilitates its functionality as a heterogeneous catalyst, by stabilizing it for at least several hours. The activity of Ni(I)L+ which is entrapped within the matrix, was studied by reducing 2,2‐Bis(bromomethyl)‐1,3‐Propanediol and I3−. The results indicate that Ni(I)L+/Ni(III)L−H2+ acts as a good reducing agent. These results have important implications for a variety of essential catalytic reactions by shedding light on a new feature of sol‐gel matrices and their use as active species stabilizers.

The effect of the ligands 2,5,8,11-tetramethyl-2,5,8,11-tetraaza-dodecane and fumarate on the mechanism and kinetics of the Cu(I) catalyzed Meerwein reaction was studied. The results point out that initially the Cu(I) ion binds to the aromatic ring with the diazo substituent. This reaction is followed by a redox process involving N2 loss and the formation of an aryl radical, R˙. The following kinetics depends on the nature of the ligand, its effect on the redox potential and the steric hindrance it induces on the central copper ion. Clearly the ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraaza-dodecane does not form an optimal catalyst with Cu(I) while it does for the Ullmann reaction.